Upgrade our markdown implementation to align with markdown-it-py==3.0.0

[miteshashar]

Validate/compare our code and plugins against the following to make relevant changes:

• 🔧 MAINTAIN: Make type checking strict executablebooks/markdown-it-py#267
  Strict type annotation checking has been applied to the codebase in markdown-it-py==3.0.0.
  Following which, the following mypy failures have surfaced and need to be corrected.

funnel/utils/markdown/mdit_plugins/heading_anchors_fix.py:45: error: Argument 3 to "after" of "Ruler" has incompatible type "Callable[[StateInline], None]"; expected "Callable[[StateCore], None]"  [arg-type]
funnel/utils/markdown/mdit_plugins/abbr.py:145: error: Argument 3 to "after" of "Ruler" has incompatible type "Callable[[StateInline], None]"; expected "Callable[[StateCore], None]"  [arg-type]
funnel/utils/markdown/mdit_plugins/toc.py:259: error: Argument 2 to "push" of "Ruler" has incompatible type "Callable[[StateInline], Any]"; expected "Callable[[StateCore], None]"  [arg-type]
funnel/utils/markdown/base.py:145: error: Argument 2 to "MarkdownIt" has incompatible type "dict[Literal['html', 'breaks', 'linkify', 'typographer'], bool]"; expected "Mapping[str, Any] | None"  [arg-type]

• 🔧 Add typing of rule functions executablebooks/markdown-it-py#283
• ‼️ Remove unused silent arg in ParserBlock.tokenize executablebooks/markdown-it-py#284